Reciprocative, double sash, gang sawmill



April 3, 1956 A. WOODRUFF 2,740,436

RECIPROCATIVE, DOUBLE SASH, GANG SAWMILL Filed Nov. 25. 1952 2 Sheets-Sheet l Zhmentor:

ALVIN WOODRUFF,

' (Ittorneg s,

United States Patent RECIPROCATIVE, DOUBLE SASH, GANG SAWMILL Alvin Woodrufi, Dallas, Greg.

Application November 25, 1952, Serial No. 322,376

3 Claims. (Cl. 143-60) This invention relates to reciprocative, double sash, gang sawmills.

The principal objects of the invention are to provide a reciprocative, double sash gang saw arrangement in combination with a driving mechanism which embodies maximum economy and smoothness of operation with compactness and stability of structure. At the same time the mechanism of the invention is adapted to be portable so that it can be moved from place to place conveniently and expeditiously.

Detailed objects of the invention appear hereinafter.

In accomplishing the objects of the invention, a frame is provided in which two vertically reciprocative sawframes or saw-sashes are mounted so as to be spaced apart from each other and to be slidable along the planes thereof, in a nearly balanced relationship to each other.

The two saw-sashes are driven by means of a twin crankshaft having connecting rods which extend to the respective saw-sashes, the stroke of the saw-sashes being determined by the throw of the cranks.

Each saw-sash is fitted with a plurality of saw blades suitably spaced apart from each other as may be determined by the thickness of the lumber to be sawed. The saw blades are divided into two groups, one group being operative upon the inner portion or heart of a log and the other group being operative upon the outer portion of the log. As a result, the two groups of blades are simultaneously effective in sawing, so that only one pass of the log through the mill is necessary to effect the complete sawing.

A convenience is, that the saw blades which cut the outer portion of the log, complete the run through the log somewhat in advance of the blades which cut the heart of the log. In this way, the outer boards can be carried out of the way before the blades, that cut through the heart of the log, complete the run. Thus, the heart portion of the log remains in position in the mill until the entire log has been run through. This assures the stability of the log during the sawing operation.

In the accompanying drawings which illustrate an excellent embodiment of the machine, 5

Fig. 1 represents a top plan, a log being shown in the process of being sawed into lumber;

Fig. 2, a side elevation;

Fig. 3, an end elevation;

Fig. 4, a fragmentary section taken on the line 4-4 in Fig. 2;

Fig. 5, a horizontal section taken on the line 5-5 in Fig. 3, drawn to an enlarged scale;

Fig. '6, an elevation of one saw-sash apart from the sawmill assembly; 5

Fig. 7, an elevation of the other saw-sash apart from the general assembly;

Fig. 8, a vertical section taken on the line 8-8 in Fig. 6.

Referring to the drawings, the numeral 10 indicates the general assembly of the sawmill.

An upright frame 11 has two pairs of posts 12, each pair being connected to each other at the top, for example by head plates 13. The lower ends of the posts.

12 are rigidly mounted on a foundation frame 14 which extends longitudinally from the front to the back of. the mill. Extending downwardly from the head 13 along the respective posts 12 are two pairs of guides 15 and extending upwardly from the foundation frame 14, along the posts 12, are two pairs of guides 16.

At 17 is a saw-sash which is slidable vertically in one pair of the lower guides 16 and in one pair of the vertical guides 15, these two pairs of guides being located in the plane of reciprocation of the front saw-sash 17. Similarly arranged for vertical sliding is the other or rear saw-sash 18.

The two saw-sashes are spaced apart from each other along the longitudinal dimension of the sawmill and determine the sawing zone. In the sawing operation, the two reciprocating saw-sashes pass each other so that one moves upwardly while the other moves downwardly and vice versa.

In the present instance, the two saw-sashes are driven by means of a crankshaft and flywheel assembly 19 located an appreciable distance above the sawing zone. Two outer wheels 20 straddle an intermediate wheel 21 and are fixed thereto by the crankpins 22. The outer wheels 2d are fixed on respective shaft portions 23. The intermediate wheel 21 advantageously has a toothed rim for meshing with a relatively heavy roller chain 24. The chain 24 extends to a countershaft pinion 25 which by means of a drive pulley 26 derives power from any suitable prime mover, such as a diesel engine (not shown).

Mounted in the sash 17 are saw blades 27, Fig. 6, which preferably are divided into two symmetrical groups. These two groups are spaced apart from each other so as to define the central opening 28 between them. In the sash 18, Fig. 7, is a centrally disposed group of saw blades 29, these blades being in central alignment with the opening 28 in Fig. 6. Obviously, the planes of the saw blades 27 in the sash 17 are spaced apart from the planes of the blades 29 in sash 18 so as to produce the desired number and thicknesses of sawed boards in Fig. 5, the spacing apart of the two saw-sashes 17 and 18 longitudinally of the mill, in other words normal to the planes of the frames 17 and 18, is clearly shown.

The lower ends of the saw blades 27 and 29 in the respective frames 17 and 18 are individually spaced and secured to the respective tail pieces 43 by clamps 44. Spaced along the respective head pieces 45 are tensioning clamps 46. These for example, may consist of clamping portions 47 ending in threaded bolts 48 sandwiched between spaced channels constituting the respective head pieces 45 with securing nuts 49.

characteristically, in the plane of crank rotation of the crankshaft, the angular spacing of the two crankpins relative to each other around the axis of rotation, is divided into two unequal angular magnitudes, such for example as A and B in Fig. 4. This means that the two crank arms are not angularly symmetrical when each is projected axially into the diametral plane of the other. In other words, the angular spacing between the two crank arms is different when counted on one side of a crank radius than it is when counted on the other'side of the same crank radius. This results in beneficially dividing each complete travel cycle of each saw-sash into two unequally timed reciprocative periods of action.

A preferred spacing is where A in Fig. 4 is approximately degrees of arc, and B is approximately 240 degrees.

Another and perhaps clearerway of expressing the above relationship is on the basis of the disposition of the two crankpins within a common diametric sector of the balanced rotative'nnit formed by' the two crank wheels- 20 and the drive wheel 21, such crankpins being advantageously spaced fromeach other within the common diametric sector by approximately 120 angular degrees.

I At 30 are carrier rollers for supporting a log 32 in its passage through the null. At 31 are rollers by means of which pressure is exerted upon the log 32. Both the carrier rollers and the pressure rollers are in frictional contact upon the log 32in its passage through the sawing zone 33. One or both sets of rollers 30 and 31 exert frictional bites upon the log.

Logs to be sawn are fed into the sawmill and are firmly gripped between the rollers 30 and 31 during the feeding and sawing operation. The log in the process of feeding through the sawmill is shown in Figs. 1, 2 and ,Access to the saw-sashes is had by means of gates 3'4 hinged on fixed standards 35. In the closed position of each gate it is held locked by a pin 37, the pin being slidable up and down in brackets 38. In the closed position of each gate the pin 37 is held in an eye 39. Pressure is exerted upon the rollers 31 by means of pistons 36 working in hydraulic or pneumatic cylinders 40, the cylinders being fixed on the gates 34. In the cylinders are reciprocatively disposed, piston rods 41, the latter at the lower ends thereof, being fixed to pistons 36. Fluid, such as oil under pressure, is admitted below each piston and pushes the respective piston rod up, the travel thereof being limited so the upper end of the rod comes into registry with a stationary bracket 42. The bracket 4'2-is forked, and the end of the rod is provided with a head 41a. Closing a gate causes the respective head 41a to slip into the corresponding forked bracket and to be held by the fork while the respective cylinder 44 and i'ts'ga'te 3'4 are lowered. Further fluid pressure admitted under the piston, acts to force the respective gate with its roller 31, down.

Fluid under pressure is supplied from any suitable source (not shown) through flexible conduits such as hoses (not shown) in any usual manner.

The feed rollers 30 and 31 in this instance, are designed to be driven directionally as indicated by the respective arrows.

' It is believed that the actual driving mechanism for the rollers 30 and 31 need not 'be specifically illustrated or described in this application since such mechanism is old in the art. Therefore, the shafts 50 and 51 in Fig. 1 and Fig. 5 are shown broken and may be disposed of with the statement that the shafts are extended beyond the indicated broken portions and are intergeared with one another and with a suitable source of power. Such intergearing may consist of sprocket wheels, sprocket chains and appurtenances in accordance with usual prior practice, but suchitems are not here illustrated since these do not constitute parts of the present invention.

Saw frames 17 and 18 are provided with upper shoes 4 e 1 52 which travel in the guides and with lower shoes 53 which travel in theguides 16, Figs. 2 and 5.

Connecting rods 54 extend from the crank pins 22 to crosshead pins 55, one of the latter being disposed in each respective head piece of frames 17 and 18.

The machine of the invention is extremely portable and is designed to be mounted on trailer wheels and appurtenances (not shown) for hitching to automotive vehicles i such as. tractors.

What is claimed is: 1. A rcciprocative, double sash, gang sawmill, comprising a supporting framework; two saw-sashes disposed for vertical reciprocation within said supporting frame-g work and along respective parallel planes which are spaced apart and aligned longitudinally of the sawmill, so as to simultaneously operate on the same work; drive means I for reciprocating said saw-sashes in opposition to each other, said drive means includinga crankshaft extending longitudinally of the sawmill and transversely of the saw: sashes, above and centrally of the latter, said crankshaft comprising, intermediate itslength, two crank wheels,

and a'drive wheel interposedbetween said crank wheels,

the said drive wheel approximating the said crank wheels in diameter and the three wheels serving as a balanced ro-' tative unit, two oppositely extending crankpins rigidly interconnecting said drive wheel with the respective crank Wheels within a common diametric sector of said unit, in mutually spaced relationship within said sector, connecting rods interconnecting said crank pins with the respective saw-sashes, and means for driving said drive wheel; and means journa'lling opposite end portions of said crankshaft on said supporting framework.

2. The sawmill of claim 1, wherein the crankpins are 7 spaced from each other within the common diametn'c sector of the balanced rotative unit by approximately angular degrees.

3. The sawmill of claim 1, wherein that saw-sash which is arranged to last engage the work is provided with a centrally disposed group of mutually spaced, individual saw blades, and wherein the other saw-sash which first engages the work is provided with two mutually spaced groups of mutually spaced, individual saw blades disposed laterally of said centrally disposed group of saw blades.

References Cited in the file of this patent :UNITED STATES PATENTS 

